The Cannes Film Festival opened last night with an experience of the most chilling and dizzying high anxiety. Blindness is an apocalyptic nightmare adapted from the 1995 novel by the Nobel laureate José Saramago and directed by Fernando Meirelles, who finds in it the brutal exposition of shanty-town jungle-law we saw in his 2002 movie City Of God.

The film is superbly shot by Cesar Charlone. In a city of the near future a terrifying epidemic of "white blindness" spreads like wildfire. People are seeing only milky white light. A Japanese businessman (Yusuke Iseya) staggers from his luxury car, which is stolen by an opportunist thief who goes blind too, then finds himself in the offices of an eye doctor (Mark Ruffalo) who is treating a prostitute (Alice Braga) with the help of a barman (Gael García Bernal). All go blind, and from this nexus the disease spreads.

The blind are herded into camps, guarded by cops in anti-infection masks who dump food to distribute themselves. A Lord Of The Flies situation develops, but Ruffalo's doctor has an advantage: secretly his wife (Julianne Moore) can see.

The city of the blind reveals the former civilisation's brutality. What is fascinating is the inmates being admitted in the order they made contact in the preceding narrative: all are linked via the heedless contact of the modern, uncaring city, and are now joined in a chain of terrible significance.

As the shuffling inmates get used to their blindness, they experience a crisis prefigured by Berkeley's 18th dictum on being and being perceived: they see no one and no one sees them. Do they exist? Did they exist before?

Other inmates see a new equality in blindness: young and old, ugly and beautiful, all are at the same level.

Blindness is a drum-tight drama, with superb, hallucinatory, images of urban collapse. It has a real coil of horror at its centre, yet is lightened with gentleness and humour. It reminded me of George A Romero's Night Of The Living Dead, and Peter Shaffer's absurdist stage-play Black Comedy. This is bold, masterly, film-making.